First year Dynamics

1. The problem statement, all variables and given/known data
Small Steel balls fall from rest through the opening at A at the steady rate of two per second. Find the vertical separation h of two consecutive balls when the lower one has dropped 3 meters.

2. Relevant equations
all kinematics equations

3. The attempt at a solution
I found the time it took for 1 ball to reach 3m which was 0.782 seconds, lost from here